1. Field
This invention relates to exercise treadmills and, in particular, to treadmills having an endless belt riding over a tread base or deck on which the treadmill user walks, jogs, or runs.
2. State of the Art
Typical treadmills include a continuous or endless belt trained about a pair of rollers. The belt has an upper stretch which extends over a tread base or deck which supports a user thereon. The base or deck is secured to a frame which generally consists of a box formed of two longitudinal members and two cross members or braces secured to the longitudinal members proximate the front end and the rear end of the machine. The rollers are attached to and between the longitudinal frame members. A front roller may be driven by a motor. Typically, the user may change the speed of the continuous belt to increase the rate at which the exerciser must walk or run in order to maintain relative position on the treadmill. Typical treadmills, as above described, are relatively expensive to manufacture and less expensive but equally durable structure is disclosed and claimed in copending U.S. Pat. Application Ser. No. 07/479,835, filed Feb. 14, 1990, assigned to the assignee of the present invention and the disclosure of which is hereby incorporated herein by this reference.
All treadmills known to us, however, even the improved treadmill of the aforementioned application, suffer from a common deficiency which is the rigid and unyielding nature of the belt supporting structure, the tread base or deck. The deck rigidity necessary to support the user as he or she strides on the endless belt is, upon long use, uncomfortable to the user in the same manner as walking, jogging, or running on an asphalt or cement roadway or walkway for extended distances. Stated another way, striding on a conventional, rigid, and rigidly mounted treadmill base or deck may jar the joints and tendons of the user, particularly at higher speeds and over longer distances. This may be particularly detrimental to those using treadmills for rehabilitative purposes.
It would be desirable to have a more yielding supporting structure for the endless belt which could be inexpensively incorporated in existing treadmill designs with little or no modification thereof.